In order to produce a long fiber reinforced thermoplastic resin pellet used as a material of injection molding or the like, the following method is known.
That is, a method includes: continuously pulling out reinforcing fiber bundles provided in a form that each reinforcing fiber bundle is wound around a bobbin, while making the reinforcing fiber bundles pass through an impregnation die, in which molten resin is stored; taking out the reinforcing fiber bundles from a die nozzle of this impregnation die as a long fiber reinforced resin strand, and then cooling down and twisting the long fiber reinforced resin strand, and then cutting off the long fiber reinforced resin strand by predetermined length into pellets (for example, refer to Patent Document 1).
The reinforcing fiber bundle is a bundle formed by gathering 2,000 to 3,000 long fibers (filaments) such as glass fiber, the bundle having an outer diameter of about 1 to 2 mm, and a shape of the bundle is retained by applying a sizing agent of polypropylene (PP) system or the like. It can be said that the sizing agent is required to maintain a gathered state in such a manner that unraveling of each long fiber is not generated and to generate flexibility like a strand.
Since a reinforcing fiber bundle is provided in the form that the reinforcing fiber bundle is wound around a bobbin (hereinafter, referred to as a wound body) as described above, each would body has a front end and a tail end. Therefore, at the time of continuously producing the long fiber reinforced thermoplastic resin pellet, every time when the wound body is replaced, there is a need for connecting a tail end of a reinforcing fiber bundle of a wound body finishing feeding of the reinforcing fiber bundle (hereinafter, also referred to as a “preceding wound body”) and a front end of a reinforcing fiber bundle of a new wound body, in which the reinforcing fiber bundle is wound.
In order to connect the reinforcing fiber bundles, both the tail end and the front end are installed in an air splicer (a device for blowing pressurized air), the fiber bundles are unraveled to long fibers with the pressurized air, and the unraveled long fibers are entwined with each other.